Shunting signals for multiple routes
A single shunting signal can apply to more than one route but sometimes it is necessary for such signals to make it clear which route has been set. An example might be at a yard outlet, where it is important to show whether the signal is cleared for a short dead-end neck or the main line. Indication of route can be critical at places where shunting movements are being propelled.
In most cases, the various types of shunting signal simply mirror their full-sized counterparts in their mode of operation.
On signal posts
Siding signals can be faithful reproductions of their full-sized counterparts. This semaphore example shows a bracket signal where the left-hand of the choice of routes is of lesser importance.
There was no colour-light equivalent, route indicators would normally be used.
To save space (and economise on cost), siding signals can be stacked above each other. The top-most arm always applies to the left-hand route, and the bottom to the right.
This arrangement is quite common with siding signals, unlike the equivalent signal with full-sized arms.
In colour-light form, route indicators were the common equivalent.
Often, a single shunting disc can apply to multiple routes, but ground disc signals can be mounted alongside each other to define separate routes. It is known to have as many as four discs alongside each other but this is often limited by space constraints.
Again, the common equivalent in colour-light form uses a route indicator.
Multiple ground discs can also be stacked vertically. This arrangement is more common than placing them alongside each other, owing the the limited space between lines.
Guess what the typical colour-light equivalent was!
The maximum number of stacked disc signals known to have existed is five, although only one such is known of. Those with four discs were common.
Another way that is used to indicate large numbers of routes, or overcome space limitations, is to provide a Route Indicator to accompany a single arm.
Route indicators can also be provided with shunting discs, allowing large numbers of different routes to be indicated without the need for a complex signal.